近似熵是系统复杂性测度很有效的一种方法，在医学、机械设备故障的诊断等方面得到广泛应用。近似熵复杂性测度具有计算简便，对时间序列长度等条件要求相对较低等优点，因而更具有实用价值，是水文非线性系统领域中的新型工具。-Approximate entropy is a measure of system complexity, a very effective way, in medicine, the diagnosis of mechanical equipment failures, etc. a

基于MATLAB的编写的近似熵算法ApEn，还可以进行后续改进，如快速近似熵算法。-Prepared based on approximate entropy MATLAB algorithm ApEn, it can also be subsequent improvements, such as fast approximate entropy algorithm.